Uncertainties in the nu p-process: supernova dynamics versus nuclear physics

Abstract

We examine how the uncertainties involved in supernova dynamics as well as in nuclear reactions affect the nup-process in the neutrino-driven winds of core-collapse supernovae. For the supernova dynamics, we find that the wind-termination by the preceding outgoing supernova ejecta, as well as the electron fraction at the onset of the nup-process, Y_{e, 3} (at 3 x 10^9 K), plays a crucial role. The wind-termination within the temperature range of (1.5-3) x 10^9 K greatly enhances the efficiency of the nup-process. This implies that the early wind phase when the innermost layer of the preceding supernova ejecta is still 200-1000 km from the center is most relevant to the p-nuclei production. The outflows with Y_{e, 3} = 0.50-0.60 result in the production of the p-nuclei up to A = 108 (108Cd) with interesting amounts, which fill the gap that cannot be accounted for by the gamma-process scenario. Furthermore, the p-nuclei up to A = 152 (152Gd) can be produced if Y_{e, 3} = 0.65 is achieved. For the nuclear reactions, we test the sensitivity to the rates relevant to the breakout from the pp-chain region (triple-alpha, 7Be(alpha, gamma)11C, and 10B(alpha, p)13C), and to the (n, p) rates on some iron-group nuclei (56Ni, 60Zn, and 64Ge). We find that a small variation of triple-alpha as well as of 56Ni(n, p)56Co leads to a substantial change in the p-nuclei production, although the others also have non-negligible effects.